1. Field of the Invention
The present invention relates to a wheeled work vehicle including front and rear wheels and a swiveling ground-work implement.
2. Description of the Related Art
A conventional art of the above type is known from Japanese Patent Application “Kokai” No. 2001-97017. In this, a traveling body having front and rear wheels mounts a swivel base via a swivel bearing and the swivel base mounts thereon an upper structure having a driver's seat and a steering unit and mounts also a ground-work implement having a liftable work tool. An engine as a portion of the upper structure is mounted on the swivel base and the driver's seat is disposed immediately above a swivel shaft. With this conventional art, the top face of the traveling body is formed flat and located higher than upper ends of the front and rear wheels and the engine is mounted on the swivel base as described above. Hence, the upper structure includes a fuel tank, a work oil tank, a hydraulic unit etc. In operation, as the engine drives a hydraulic pump, the pump feeds its work oil to a traveling hydraulic motor mounted on the traveling body, so that the front and rear wheels are driven via a transmission mechanism.
The above-described conventional vehicle is capable of traveling at a high speed on the road with its front and rear wheels and capable also of effecting such ground work as digging with swiveling the ground-work implement and also lifting up/down its work tool. However, as the engine is mounted on the swivel base, the upper structure significantly projects rearward, thus presenting an extremely large distance from the swivel shaft to the rear end of the structure. Moreover, this rear end further projects significantly from the rear ends of the rear wheel. As a result, traveling stability cannot be obtained and also a swiveling operation within a limited space is very difficult.
Moreover, the swivel base mounts thereon not only the engine, but also other components as the fuel tank, the oil tank, the hydraulic unit, etc., so that the center of gravity of the vehicle is located at a relatively high level. This makes improvement in the traveling stability difficult. And, the significant total mass of the upper structure makes improvement in the swiveling operability difficult.
In addition, the ground-work implement can effect only vertical pivotal movements. Hence, even with swiveling of the swivel base, the ground work is possible only forwardly of the driver's seat. Hence, this conventional vehicle cannot cope with a work such as a side ditch digging for digging the ground near a wall or the like which is effected typically by a backhoe. Consequently, this conventional vehicle is disadvantageous in being limited in the type of work possible as well as in presenting significant difficulty in a digging operation within a limited space.